In the medical industry, an X-ray apparatus refers to an apparatus that causes an amount of X-rays to pass through a part of a human body to obtain an image therefrom, receives X-rays that have passed through the body part using an X-ray sensor, and provides an image using electrical signals caused based on received X-rays. Since X-rays that have passed through the body part cause different electrical signals according to the X-ray absorption ratios of individual locations of the body part, an image can be produced by processing the electrical signals using a central processing unit of the X-ray apparatus.
In the dental industry, an X-ray computed tomography (CT) apparatus refers to an apparatus that produces a tomographic image or, as required, a three-dimensional (3D) image of a set of teeth, the jaw joint, or the head, which is a main part of concern of body parts of a patient, by obtaining X-ray images of the body part at a variety of angles while rotating around the entire portions of the body part and then reconstructing the obtained X-ray images.
In the dental X-ray CT apparatus of the related art, an X-ray generator is disposed on one side of a rotary arm, and an X-ray sensor is disposed on the other side of the rotary arm to face the an X-ray generator. Both the X-ray generator and the X-ray sensor are cased. As the rotary arm rotates about the fixed axis of rotation above the head of a patient, the X-ray generator and the X-ray sensor obtain a plurality of X-ray images while rotating around the dental arch of the patient. The X-ray images are obtained through rotation to an angle of about at least 200° according to image reconstruction schemes. After first image obtaining, in general, the X-ray sensor and the X-ray generator are rotated again in the direction of rotation during first image obtaining in order to move the X-ray sensor and the X-ray generator to the initial positions for second image obtaining.
In general, the X-ray sensor rotates with the smaller radius to the center of the head of the patient, and the X-ray generator rotates with the larger radius to the center of the head of the patient. When the CT apparatus is installed, a space for the maximum radius of rotation is required. Thus, the space which is greater than the actual size of the apparatus is necessary. In addition, in the case of high-speed scanning, the X-ray generator and the X-ray sensor rotating at high speed may cause the patient nervous and to make him/her move. The movement may lead to a motion artifact that degrades image quality.